1. Field of the Invention
The present invention relates to an operation microscope, and in particular to an operation microscope that is applicable to an ophthalmologic operation.
2. Description of the Related Art
With the recent advancement of the aging society and the like, there has been a growing demand for ophthalmologic operations than before. An eye (eye to be operated) of a patient that is the subject of an ophthalmologic operation has an extremely minute and delicate structure, so that it is common practice to conduct the operation while observing the eye to be operated using a microscope.
As an example of such an operation microscope, there is known a microscope disclosed in JP 2002-350735 A (hereinafter referred to as the “known document 1”), for instance. This operation microscope has a construction where a front lens for illuminating an eye to be operated is provided between an optical system including an objective lens and the eye to be operated, a lens unit for converting an inverted image of the eye to be operated obtained through the front lens into an erected image is provided so as to be insertable and removable from an optical path of the optical system, the moving direction of the front lens and the optical system by a moving apparatus is switched based on whether the lens unit is inserted onto the optical path. With this operation microscope, there is eliminated the necessity to hold a light guide in one hand unlike in the case of a conventional ophthalmologic operation, so that it becomes possible for an operator to freely use his/her both hands and to appropriately move the front lens and the optical system while observing the eye to be operated. Consequently, the accuracy and swiftness of an operation are improved.
Also, JP 2001-275978 A (hereinafter referred to as the “known document 2”) discloses an ophthalmologic apparatus provided with a binocular stereomicroscope. This ophthalmologic apparatus has a construction allowing control so that depending on whether the anterior portion of an eye to be examined is to be observed or the retina or the vitreous body thereof is to be observed, a stereo angle conversion portion and a color temperature conversion element are inserted/removed onto/from right and left optical axes by changing the position of a frame. In more detail, when the frame is set closer to the eye to be examined in order to observe the anterior portion, a position detection switch detects this situation and a control processing unit inserts the stereo angle conversion portion and the color temperature conversion element onto the right and left optical axes based on the detected result. On the other hand, when the frame is set away from the eye to be examined in order to observe the retina or the vitreous body, the position detection switch detects this situation and the control processing unit retracts the stereo angle conversion portion and the color temperature conversion element from the right and left optical axes based on the detected result.
Further, the ophthalmologic apparatus provided with the stereomicroscope described in the known document 2 is constructed so that whether an auxiliary lens (contact lens) for observing the eyefundus of the eye to be examined is inserted into the space between the eye to be examined and the objective lens is detected, and the insertion/removal of the stereo angle conversion portion and/or the color temperature conversion element onto/from the right and left optical axes is controlled based on the detected result.
In some cases, during an ophthalmologic operation, a microscope is used while performing switching between various observation modes. Therefore, the conventional operation microscope described above is constructed so that it is possible to insert/remove the front lens onto/from the optical path by swinging a holding arm depending on the purpose of usage. When it is desired to observe the retina or the vitreous body of the eye to be operated, for instance, the front lens is arranged between the objective lens and the eye to be operated and is used. On the other hand, at the time of observation of the anterior portion of the eye to be operated or at the time of use of the contact lens, for instance, it is required to swing and retract the front lens.
Also, at the time when the use/retraction of the front lens is switched, it is required to change the irradiation angle of an illumination light flux, to adjust the position of the objective lens with respect to the eye to be operated, and to switch the arrangement of the lens unit. Consequently, the operator is required to perform manipulations such as the changing of the irradiation angle of the illumination light flux, the insertion/removal of the lens unit onto/from the optical path, the adjustment of the position of the objective lens, and the like in accordance with the use/retraction of the front lens. Accordingly, it cannot be necessarily said that manipulability during an operation is favorable, and this becomes one factor that hinders the smooth conduct of the operation.
Further, with the conventional operation microscope described in the known document 1, the front lens can be inserted into the space between the eye to be operated and the objective lens under a state where the objective lens is positioned close to the eye to be operated. Also, the objective lens and the front lens can be set closer to the eye to be operated under a state where the front lens is inserted. Consequently, there is a danger that the front lens may hit the eye to be operated.
On the other hand, with the ophthalmologic apparatus provided with the stereomicroscope described in the known document 2, the control of the insertion/removal of the optical elements is performed only based on the detected result of the position of the frame or the position of the auxiliary lens and the optical elements, whose insertion/removal is controlled, are limited to the stereo angle conversion portion and the color temperature conversion element. Consequently, it is difficult to apply this technique to an operation microscope.
It is conceived that this is due to the following reason. The movement of the frame in the case of the ophthalmologic apparatus corresponds to the upward/downward movement of an optical system with respect to an eye to be operated in the case of an operation microscope, and this upward/downward movement of the optical system is performed in accordance with the presence or absence of a front lens (in response to switching between observation methods), whereby it is difficult to sufficiently enhance manipulability only through the control of the insertion/removal of the stereo angle conversion portion (stereo variator) and the color temperature conversion element. That is, in the case of the operation microscope, the upward/downward movement of the optical system is performed in accordance with the manual insertion/removal of the front lens in many cases and, in such cases, it is required to separately perform manipulation for upwardly/downwardly moving the optical system in addition to the insertion/removal of the front lens. Consequently, it is hard to say that excellent manipulability is attained.